Abstract Comprehensive School Physical Activity Programs (CSPAP) and ?whole of school? approaches have been widely endorsed due to their ability to impact youth in different settings across the school day. To promote obesity prevention, CSPAP models must also be extended to facilitate nutrition education and healthy eating. The proposed study fills an important gap in school-based obesity prevention by systematically incorporating comprehensive energy balance education and behavioral strategies at the middle school level. To date, there are no examples of hierarchically structured CSPAP interventions that can work across multiple school levels. To promote healthy youth development in schools it is essential to institutionalize programming at multiple levels and to facilitate district-wide policy change. The proposed study is built on the SWITCH? program, a USDA-funded childhood obesity prevention program directed by our research team to target elementary school students. Building SWITCH training and modules at the middle school level will extend its reach and impact to older youth, a population with reduced physical activity level and increased obesity rate. The uniqueness of the project is that we provide training and resources through a robust content management system (CMS) to enable the local school wellness leaders to be the agents of change for school wellness programming. Through the integration of the modules, the school SWITCH team will build competency in youth (e.g., knowledge and skills) and create healthier school environments for sustained obesity prevention. We will evaluate the impact of prior experience with SWITCH and current engagement with SWITCH on lifestyle knowledge and behaviors known to influence risk of obesity. Twelve rural middle schools will be recruited and assigned to two groups (4 experienced schools vs. 8 nave schools). Matching two nave schools to each experienced school is purposely planned to provide more precise estimates of the treatment effect. It is hypothesized that prior exposure to SWITCH in elementary school will amplify the effectiveness of SWITCH programming in middle school and lead to stronger outcomes (Aim 1) and that individual- and school-level engagement will also impact the effectiveness of SWITCH programming (Aim 2). Multi-level modeling analyses will be conducted by an experienced biostatistician to address the two research aims. The proposed study capitalizes on an ongoing line of work by our interdisciplinary research team and offers considerable promise for school-based childhood obesity prevention programming. The complementary skills and experiences of our research team will enable us to successfully complete the project and to build towards more comprehensive R01 grants to fully evaluate the SWITCH program at the middle school level.